US20130078901A1 - Cooling systems and methods for data centers - Google Patents

Abstract

A cooling system for selectively cooling the hot aisles of a data center is disclosed. The cooling system includes a source of cooling air, a relief damper configured to selectively allow cooling air from the source of cooling air to enter directly into the hot aisle, and a mechanism to move the relief damper between open and closed positions.

Description

BACKGROUND
• 1. Field of the Invention
• This invention relates to data center cooling systems and methods. In particular, this invention relates to systems and methods for cooling data centers having hot aisles.
• 2. Background of the Invention
• A typical data center includes spaced rows of IT racks that contain and/or support a variety of IT hardware/equipment. The IT hardware/equipment contained in and supported by those racks, and the associated peripheral equipment and cables, generate a relatively high amount of heat. Because of that heat, providing adequate cooling to the IT racks in the data center is of paramount importance. Moreover, it is desirable that the IT racks be cooled as efficiently as possible, as the energy costs to cool the IT racks may approach a large percentage of the energy costs to operate the data center.
• As stated, the IT racks in a data center are usually in spaced rows, such that aisles are formed between adjacent rows. A recognized method to increase cooling system efficiency in data centers is to have some of those aisles be dedicated cold aisles and some of those aisles be dedicated hot aisles. A cold aisle is an aisle that receives cooling air from a source of cooling air and provides it to an IT rack or multiple IT racks. A hot aisle is an aisle that receives the air after it passes through an IT rack or multiple IT racks and serves as a conduit or passageway for that air to enter an data center air exit conduit or as the exit conduit itself. Thus, the path of cooling air is from the source of cooling air, through the cold aisles, through one or more IT racks, through the hot aisles, and directly out of the data center or to a data center air exit conduit.
• In a cold/hot aisle arrangement, the air paths through the cold aisles and hot aisles are wholly or partially segregated, to ensure the elimination of or to minimize commingling of the air in the two types of aisles. This prevents the air in the hot aisles from increasing the temperature of the air in the cold aisles before the air in the cold aisles passes through the IT racks.
• Data centers typically have a raised floor system, often called an access floor system. An access floor system is usually comprised of a continuous array of floor panels, arranged edge-to-edge, and supported above the sub-floor by support structure. The array of access floor panels usually extends wall-to-wall in the data centers. The IT racks are placed on top of and supported by the array of floor panels.
• A plenum is formed between the sub-floor and the access floor panel array. The cables and other equipment run through the plenum, and the plenum is also used as a conduit for cooling air. Often, one or more air conditioning units supply air to the plenum, and some of the access floor panels in the array have grates and/or other openings. The cooling air passes through the grates and other openings into the data center.
• In a typical data center having an access floor system and hot and cold aisles, the cooling air passes through the grates or other openings into the cold aisles. The cooling air then enters the faces of the IT racks that partially form the cold aisles, and passes through the IT racks, cooling the hardware/equipment contained in and/or supported by the IT racks. The cooling air next exits the IT racks, as heated air, and enters into one of the hot aisles. The heated air in the hot aisles is then cycled back to one or more air conditioning units through a return duct.
• One way to increase the efficiency of a data center cooling system is to increase the temperature of the cooling air provided to the cold aisles. However, this increase in the cold aisle temperature results in increased temperatures in the hot aisles during normal operation, because the delta temperature value, which is the rise in temperature as the air passes through the IT racks, remains substantially the same for the same IT rack. That is, the delta temperature value will be substantially the same, regardless of the starting temperature of the cooling air in the cold aisles.
• The increase in cooling air temperatures, coupled with a gradual increase in IT equipment/hardware delta temperature values, further results in even higher hot aisle temperatures. For example, delta temperature values in present IT equipment/hardware can range from 25-60° F., while supply temperatures based on ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) recommendations can be as high as 80.6° F., resulting in possible hot aisle temperatures in up to about of 140° F.
• The elevated hot aisle temperatures are acceptable when the hot aisles are not occupied (e.g., when a technician is not working in the hot aisles). However, the elevated hot aisle temperatures can greatly affect the amount of time a technician can be expected/allowed to work in the hot aisles. For example, the maximum working conditions with a 25% work cycle/75% rest cycle is approximately 117° F. Continuous work requirements require further reduction of the temperature in the hot aisle.
SUMMARY
• In view of the above, it is desirable and energy efficient to reduce the temperature in a hot aisle of a data center when a person is going to be in the hot aisle, but to allow the temperature in the hot aisle to be higher when no one is in the hot aisle.
• The data center cooling system of this invention is for a data center having at least one hot aisle and at least one cold aisle. The system includes a relief damper that is configured to selectively allow cooling air from the source of cooling air to enter directly into the hot aisle. The system includes a mechanism that controls the position of the relief damper between open and closed positions. The relief damper, when open, permits air to pass from the plenum to the hot aisle and, when closed, prevents air from passing from the plenum into the hot aisle. There can be multiple open positions, if desired.
• In some embodiments of the invention, the source of cooling air is a plenum formed between the array of panels of a raised access floor system and the subfloor.
• According to other embodiments, the relief damper may be operated by a manual switch that switches the relief damper from the closed position to an open position, and vice versa.
• The cooling systems of this invention may include an indicator that signals that the relief damper is in an open position. The indicator may provide a visual signal and/or an audio signal. The indicator may be powered by an airflow through the relief damper when it is in an open position.
• According to other embodiments, the data center cooling system may have a hot aisle occupation sensor unit that senses when a person is in the hot aisle. The data center cooling system may have a control unit that controls the relief damper based on the output of the hot aisle occupation sensor unit. The hot aisle occupation sensor unit may comprise a motion or pressure sensor to detect the presence of a person in the hot aisle.
• In other embodiments, the control unit may control the relief damper based on the temperature sensed by a temperature sensor in the hot aisle.
• According to other embodiments, an actuator may be provided outside the hot aisle that, upon being actuated, signals or instructs the cooling system to reduce the temperature in the hot aisle by opening the relief damper.
• In certain embodiments, a display unit may also be positioned outside the hot aisle. The display unit may indicate the temperature in the hot aisle. The display unit may also display whether it is permissible to enter the hot aisle, for example, by displaying a red light, indicating that a temperature in the hot aisle is too high, or a green light, indicating that a temperature in the hot aisle is acceptable.
• Another aspect of this invention is a method for selectively and directly cooling a hot aisle of a data center. The method may comprise selectively opening a relief damper located between a source of cooling air and the hot aisle to directly provide cooling air from the source of cooling air to the hot aisle.
• According to another embodiment, the method for selectively and directly cooling a hot aisle of a data center may further comprise sensing whether a person is in the hot aisle, and controlling the relief damper based on the output of the sensor.
BRIEF DESCRIPTION OF THE DRAWINGS
• Various exemplary embodiments of this invention will be described in detail with reference to the drawings in which:
• FIG. 1 is a schematic view of a data center cooling system according to one embodiment.
• FIG. 2 is a schematic view of a data center cooling system according to another embodiment.
• FIG. 3 is a block diagram illustrating selected components of the data center cooling system according to the embodiment ofFIG. 2.
DETAILED DESCRIPTION OF EMBODIMENTS
• As illustrated inFIG. 1, a data center typically includes one or moreair conditioning units10, anaccess floor system15 that consists of an array ofaccess floor panels17 supported above the subfloor16 and positioned edge-to-edge to form a continuous raised floor surface abovesubfloor16, one or more IT racks20, and areturn air plenum65.
• The IT racks20 are supported by theaccess floor panels17 and are usually positioned in spaced rows. The IT racks20 contain and/or support IT hardware and other data center electronic equipment.
• Hot aisles70 andcold aisles30 are formed on opposite sides of the rows of IT racks20. Air in thehot aisles70 and thecold aisles30 is precluded, partially or wholly, from commingling.
• WhileFIG. 1 illustrates a data center having only two IT racks20, twocold aisles30 and onehot aisle70, it should be understood that data centers in which the cooling system of this invention can be utilized can include any number of IT racks20 (arranged in any number of rows),cold aisles30 andhot aisles70.
• Theair conditioning unit10 provides cooling air A toplenum60 formed between the array ofaccess floor panels17 and thesubfloor16. The cooling air A passes through grates or other openings in the array ofaccess floor panels17 intocold aisles30.
• The cooling air then passes fromcold aisles30 into the sides of the IT racks20 that partially form thecold aisles30 and through those racks, thereby cooling the IT equipment/hardware contained in and/or supported by the IT racks20. The cooling air is next exhausted from the opposite sides of the IT racks20, as heated exhaust air B, into thehot aisle70. An airflow C exits thehot aisle70 and enters thereturn plenum65, forming a return airflow D that is cycled back to theair conditioning unit10.
• The cooling air A that is provided to thecold aisles30 can be, for example, 80° F. or more. As discussed above, having a cooling air temperature of 80° F. or more may result in temperatures in thehot aisles70 in excess of 140° F., which is undesirably high during periods in which a technician needs to be in thehot aisle70 to perform maintenance or other work on the IT equipment/hardware that is contained in and/or supported by the IT racks20.
• In theFIG. 1 embodiment of this invention, one ormore relief dampers40 are provided in or adjacent to openings in the array ofaccess floor panels17 to selectively allow the cooling air A to pass directly to thehot aisle70.FIG. 1 illustrates tworelief dampers40, but the number ofrelief dampers40 is not limited to two, and any number ofrelief dampers40 can be employed.
• Therelief dampers40 have at least one open position and a closed position. The cooling air A is allowed to pass directly from theplenum60 to thehot aisle20 when therelief dampers40 are in the open position(s). Conversely, when therelief dampers40 are in the closed position, they prevent the cooling air A from passing directly into thehot aisle70. Therelief dampers40 may have various open positions, such that the quality of air that passes through them varies, depending on the selected open position.
• When therelief dampers40 are in an open position, the entry of cooling air A directly into thehot aisle70 reduces the temperature in thehot aisle70, at least temporarily. Technicians can enter thehot aisle70 during periods when the temperature in thehot aisle70 is reduced to maintain, service or do other work on the IT equipment/hardware contained in and/or supported by IT racks20.
• In the embodiment illustrated inFIG. 1, therelief dampers40 are moved from their closed position to an open position, and vice versa from an open position to their closed position, by means of a manually operatedswitch50, which can be provided inside or outside thehot aisle70. The manually operatedswitch50 can be, for example, a lever or other mechanism that is operated by hand, or a mechanism that is operated by a tool.
• Anindicator80 may be provided that indicates when therelief dampers40 are in open and/or closed positions. Theindicator80 may be a visual indicator or an audio indicator. One function of theindicator80 is to remind a technician working in thehot aisle70 that therelief dampers40 are still in an open position when the technician is done working in thehot aisle70, so that the technician changes the position of therelief dampers40 from an open position to the closed position at the conclusion of his/her work session. If the indicator is a visible indicator, it may be a blinking red light, or any other type of visible indicator. If the indicator is an audio indicator, it may provide a beeping or buzzing noise that is loud enough to be heard over the noise generated by the IT hardware/equipment contained in and/or supported by IT racks20. In the case where the visual and/or audio indicators require power to operate, the power can be provided via a turbine that generates power via the cooling air A passing through therelief dampers40. Alternatively, the indicator can also be electrically powered, such as by a battery or a direct electrical connection to an outlet.
• FIG. 2 illustrates another embodiment of this invention in which therelief dampers40 are electronically controlled instead of being manually controlled. The system illustrated in the embodiment ofFIG. 2 includes an actuator, such as anenter button90, that is actuated when a technician wants to work in thehot aisle70. Theenter button90 may be provided outside thehot aisle70, either in acold aisle20, as shown inFIG. 2, or outside the data center.
• In this embodiment, upon depressing theenter button90, therelief dampers40 are opened via amotor160 to allow cooling air A to enter thehot aisle70. Theenter button90 may also control the opening of a door or other closure into thehot aisle70. That is, whenbutton90 is activated, it may cause both therelief dampers40 to move from the closed to an open position and the door or other closure to thehot aisle70 to open. While a button is illustrated in the figures and discussed above, any other actuator switch mechanism can be utilized.
• Atemperature sensor150 may be provided to monitor the temperature in thehot aisle70. The temperature in thehot aisle70 may be displayed on adisplay unit100. Thedisplay unit100 may include a red light or other signal indicating that it is not acceptable to be in thehot aisle70, and may include a green light or other signal indicating that it is acceptable to be in thehot aisle70.
• The embodiment illustrated inFIG. 2 may also include asensor110 that detects a person in thehot aisle70. Thesensor110 may, for example, use infrared light or laser light to detect a person in thehot aisle70. Thesensor110 may be a motion sensor, one or more pressure sensors provided in the floor of thehot aisle70, or any other type sensor that would detect a person in thehot aisle70.
• Output from thesensor110 may be utilized to exclusively determine whether therelief dampers40 should be in the open position or closed position. That is, the system can be designed such that the relief dampers are opened and remain open when a person is detected in thehot aisle70. The relief dampers are closed if a person is not detected for a predetermined amount of time.
• Thesensor110 can also function as an auxiliary control for the relief dampers. For example, there can be another mechanism that is employed to move the relief damper to the open position, and the relief damper will remain in the open position for as long as the sensor senses a person in the hot aisle or for a certain period of time after the sensor ceases sensing a person in the hot aisle.
• As illustrated in the block diagram ofFIG. 3, acontrol unit120 controls the operation of therelief dampers40 in the embodiment illustrated inFIG. 2. Thecontrol unit120 may receive a signal from theenter button90 and controls themotors160 to open or close therelief dampers40 based on that signal. Thecontrol unit120 may also receive a signal fromsensor110 and the control themotors160 based on that signal, in whole or in part, as discussed above. Thecontrol unit120 also controls thedisplay unit100 to display the temperature in thehot aisle70 based on the output of thetemperature sensor150. Thecontrol unit120 may also automatically control the degree of openness of therelief dampers40 based on an output of thetemperature sensor150. Thecontrol unit120 may be a central processing unit (CPU) provided in a computer having a memory such as a flash memory, ROM or hard drive.
• The exemplary embodiments of the data room cooling system and method discussed above and illustrated by the figures are intended to be illustrative and not limiting. Various changes may be made without departing from the spirit and scope of the invention. For example, providing the cooling air to the cold aisles and the hot aisles via a plenum in an access floor system and through grates or other openings in the array of access floor panels is but one way of providing the cooling air to those aisles. The cooling air may be provided to those aisles through any other means and this invention is not limited particularly to data centers having a raised access floor system. Similarly, while the return air plenum is illustrated in the ceiling of the data room in the Figures, that plenum can be located anywhere so long as it forms a conduit between the hot aisles and the air-conditioning units.

Claims (40)

What is claimed is:

1. A cooling system for a data center that includes a plurality of IT racks and at least one cold aisle and at least one hot aisle that are located on opposite sides of at least one of the plurality of IT racks, the opposite sides of the at least one of the plurality of IT racks partially defining the at least one cold aisle and the at least one hot aisle, the cooling system comprising:

a source of cooling air that supplies cooling air to the at least one cold aisle;

a relief damper configured to selectively allow the cooling air from the source of cooling air one to enter directly into the at least one hot aisle; and

a mechanism to control movement of the at least one relief damper between open and closed positions.

2. The cooling system for a data center according toclaim 1, wherein

the source of cooling air includes a plenum formed below panels of an access floor system and the relief damper is positioned in an opening in the panels.

3. The cooling system for a data center according toclaim 2, wherein the mechanism is a mechanical actuator.

4. The cooling system for a data center according toclaim 3, further comprising an indicator that emits a signal when the relief damper is in the open position.

5. The cooling system for a data center according toclaim 1, wherein the mechanism is a mechanical actuator.

6. The cooling system for a data center according toclaim 1, further comprising an indicator that emits a signal when the relief damper is in the open position.

7. The cooling system for a data center according toclaim 1, wherein the mechanism is an electric actuator.

8. The cooling system for a data center according toclaim 7, further comprising an indicator that emits a signal when the relief damper is in the open position.

9. The cooling system for a data center according toclaim 8, wherein the signal is generated by an airflow through the relief damper when the relief damper is in the open position.

10. The cooling system for a data center according toclaim 7, wherein the mechanism causes both the relief damper to move from the closed position to the open position and a data center closure to open to permit access to the at least one hot aisle.

11. The cooling system for a data center according toclaim 1, further comprising:

a hot aisle occupation sensor that senses whether a person is present in the at least one hot aisle;

wherein output from the hot aisle occupation sensor is used to at least partially control the position of the relief damper.

12. The cooling system for a data center according toclaim 11, wherein the hot aisle occupation sensor comprises a motion sensor.

13. The cooling system for a data center according toclaim 1, further comprising:

an actuator positioned outside the at least hot aisle that, upon being actuated, signals the cooling system to open the relief damper.

14. The cooling system for a data center according toclaim 13, further comprising:

a display unit that is positioned outside the at least one hot aisle and that indicates the temperature in the at least one hot aisle.

15. A method for selectively, directly cooling a hot aisle of a data center comprising:

providing a source of cooling air for the data center;

selectively opening a relief damper to allow cooling air from the source of cooling air to directly enter the hot aisle; and

closing the relief damper to prevent the cooling air from the source of cooling air from directly entering into the hot aisle.

16. The method for selectively, directly cooling a hot aisle of a data center according toclaim 14, wherein the source of cooling air is a plenum formed below panels of an access floor system and the relief damper is positioned in an opening in the panels.

17. The method for selectively, directly cooling a hot aisle of a data center according toclaim 14, wherein the relief damper is operated by a manual actuator.

18. The method for selectively, directly cooling a hot aisle of a data center according toclaim 14, further comprising:

operating the relief damper by an electric actuator provided outside the hot aisle.

19. The method for selectively, directly cooling a hot aisle of a data center according toclaim 14, further comprising:

sensing whether a person is present in the hot aisle; and

controlling the relief damper based on whether a person is in the hot aisle.

20. The method for selectively, directly cooling a hot aisle of a data center according toclaim 14, further comprising the step of indicating when the relief damper is in the open position.

21. In a data center having at least one IT rack, at least one hot aisle, at least one cooling aisle, and a source of cooling air, the improvement comprising:

a relief damper to selectively allow cooling air from the source of cooling air directly into the at least one hot aisle; and

a mechanism to control the relief damper between open and closed positions.

22. The improvement for a data center according toclaim 21, wherein

the source of cooling air includes a plenum formed below panels of an access floor system and the relief damper is positioned in an opening in the panels.

23. The improvement for a data center according toclaim 22, wherein the mechanism is a mechanical actuator.

24. The improvement for a data center according toclaim 23, further comprising an indicator that emits a signal when the relief damper is in the open position.

25. The improvement for a data center according toclaim 21, wherein the mechanism is an electric actuator.

26. The improvement for a data center according toclaim 25, wherein the mechanism causes both the relief damper to move from the closed position to the open position and a data center closure to open to permit access to the at least one hot aisle.

27. The improvement for a data center according toclaim 21, further comprising:

a hot aisle occupation sensor that senses whether a person is present in the at least one hot aisle;

wherein output from the hot aisle occupation sensor is used to at least partially control the position of the relief damper.

28. The improvement for a data center according toclaim 27, wherein the hot aisle occupation sensor comprises a motion sensor.

29. The improvement for a data center according toclaim 21, further comprising:

an actuator positioned outside the at least one hot aisle that, upon being actuated, signals the mechanism to move the relief damper from the closed position to the open position.

30. The improvement for a data center according toclaim 29, further comprising:

a display unit that is positioned outside the at least one hot aisle and that indicates the temperature in the at least one hot aisle.

31. A data center comprising:

at least one IT rack;

a source of cooling air;

at least one hot aisle on one side of the at least one IT rack;

at least one cold aisle on a second side of the at least one IT rack, the cold aisle receiving cooling air from the source of cooling air;

a relief damper that selectively allows the cooling air from the source of cooling directly into the at least one hot aisle; and

a mechanism to control the relief damper between open and closed positions.

32. The data center according toclaim 31, wherein

the source of cooling air includes a plenum formed below panels of an access floor system and the relief damper is positioned in an opening in the panels.

33. The data center according toclaim 32, wherein the mechanism is a mechanical actuator.

34. The data center according toclaim 33, further comprising an indicator that emits a signal when the relief damper is in the open position.

35. The data center according toclaim 31, wherein the mechanism is an electric actuator.

36. The data center according toclaim 35, wherein the mechanism causes both the relief damper to move from the closed position to the open position and a data center closure to open to permit access to the at least one hot aisle.

37. The data center according toclaim 31, further comprising:

a hot aisle occupation sensor that senses whether a person is present in the at least one hot aisle;

wherein output from the hot aisle occupation sensor is used to at least partially control the position of the relief damper.

38. The data center according toclaim 31, wherein the hot aisle occupation sensor comprises a motion sensor.

39. The data center according toclaim 31, further comprising:

actuator positioned outside the at least hot aisle that, upon being actuated, signals the mechanism to move the relief damper from the closed position to the open position.

40. The data center according toclaim 39, further comprising:

a display unit that is positioned outside the at least one hot aisle and that indicates the temperature in the at least one hot aisle.

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